Coating Composition

Abstract

A coating composition for a food and/or beverage container comprising a polyester material, the polyester material comprising the reaction product of; (a) 1,2-propanediol, (b) terephthalic acid, and (c) a molecular weight increasing agent, characterised in that the polyester material has a number-average molecular weight (Mn) of at least 6,100 Da and a glass transition temperature (Tg) of at least 80° C., wherein the molecular weight increasing agent comprises a polyacid, a polyol or a combination thereof, the polyacid comprises a diacid of formula (I) wherein each R independently represents hydrogen or an alkyl, alkenyl, alkynyl, or aryl group; n=0 or 1; X represents a bridging group selected from: an alkylene group; an alkenylene group; an alkynylene group; an arylene group; the bridge between the —COOR groups is C 1 or C 2 , and the hydroxyl groups of the polyol are connected by a C 1 to C 3 alkylene group.

1 . A coating composition for a food and/or beverage container comprising a polyester material, wherein the polyester material comprises the reaction product of;
 (a) 1,2-propanediol,   (b) terephthalic acid, and   (c) a molecular weight increasing agent,   
       characterised in that the polyester material has a number-average molecular weight (Mn) of at least 6,100 Da and a glass transition temperature (Tg) of at least 80° C.; 
       wherein the molecular weight increasing agent (c) comprises a polyacid, a polyol or a combination thereof; 
       wherein the polyacid comprises a diacid of general formula (I) 
       
         
           
           
               
               
           
         
       
       wherein each R independently represents hydrogen or an alkyl, alkenyl, alkynyl, or aryl group; n=0 or 1; wherein X represents a bridging group selected from: an alkylene group; an alkenylene group; an alkynylene group; an arylene group; wherein the bridge between the —COOR groups is C 1  or C 2 ; 
       and wherein the hydroxyl groups of the polyol are connected by a C 1  to C 3  alkylene group. 
     
     
         2 . A coating composition according to  claim 1 , wherein the polyacid comprises maleic anhydride or itaconic acid or a combination thereof 
     
     
         3 . A coating composition according to either of  claim 1  or  2 , wherein the polyol comprises trimethylolpropane, glycerol or a combination thereof. 
     
     
         4 . A coating composition according to any preceding claim, wherein the molar ratio of (a):(b) ranges from 5:1 to 1:5. 
     
     
         5 . A coating composition according to any preceding claim, wherein the molar ratio of (a)+(b):(c) ranges from 100:1 to 1:1. 
     
     
         6 . A coating composition according to any preceding claim, wherein the coating compositions comprise from 1 to 100 wt % of the polyester material based on the total solid weight of the coating composition. 
     
     
         7 . A coating composition according to any preceding claim, wherein the coating composition further comprises a crosslinking agent. 
     
     
         8 . A coating composition according to  claim 7 , wherein the crosslinking agent comprises a phenolic resin. 
     
     
         9 . A coating composition according to any preceding claim, wherein the polyester material has a gross hydroxyl value (OHV) from 0 to 30 mg KOH/g. 
     
     
         10 . A coating composition according to any preceding claims, wherein the polyester material has an acid value (AV) from 0 to 20 mg KOH/g. 
     
     
         11 . A coating composition according any preceding claim, wherein the coating composition comprises from 1 to 100 wt % of the polyester material based on the total solid weight of the coating composition. 
     
     
         12 . A coating composition according to any preceding claim, wherein the coating composition further comprises an additive or combination of additives. 
     
     
         13 . A coating composition for a food and/or beverage container comprising a polyester material, wherein the polyester material comprises the reaction product of a one step process, the one step process comprising contacting:
 (a) 1,2-propanediol,   (b) terephthalic acid, and   (c) a polyol molecular weight increasing agent,   
       characterised in that the polyester material has a number-average molecular weight (Mn) of at least 6,100 Da and a glass transition temperature (Tg) of at least 80° C.; 
       wherein the molecular weight increasing agent (c) comprises a polyacid, a polyol or a combination thereof; 
       wherein the polyacid comprises a diacid of general formula (I) 
       
         
           
           
               
               
           
         
       
       wherein each R independently represents hydrogen or an alkyl, alkenyl, alkynyl, or aryl group; n=0 or 1; wherein X represents a bridging group selected from: an alkylene group; an alkenylene group; an alkynylene group; an arylene group; wherein the bridge between the —COOR groups is C 1  or C 2 ; 
       and wherein the hydroxyl groups of the polyol are connected by a C 1  to C 3  alkylene group. 
     
     
         14 . A coating composition according to any preceding claim, which is substantially free of bisphenol A (BPA) and derivatives thereof. 
     
     
         15 . A food and/or beverage container coated on at least a portion thereof with a coating composition of any of the preceding claims.